Ga 0.51 In 0.49 P/In x Ga 1−x As/GaAs lattice-matched and strained doped-channel field-effect transistors grown by gas source molecular beam epitaxy

Abstract

Recently, it was demonstrated that doped-channel field-effect-transistor (DCFET) structure has the advantages of high breakdown voltage, high current drivability, and high turn on voltage. Therefore, a series of lattice-matched and strained Ga0.51In0.49P/InxGa1−xAs/GaAs (0⩽x⩽0.22) DCFETs were studied in order to find the optimized structure. Through dc and microwave measurements, we observed that the introduction of a 150-Å-thick strained InxGa1−xAs (0.15⩽x⩽0.22) channel can enhance device performance, compared to the lattice-matched one (x=0). The optimized performance of transconductance (gm), current-gain cutoff frequency (ft) and maximum oscillation frequency (fmax) all occurred when indium content x was between 0.15 and 0.20 for devices with 1-μm-long gate and these optimized results are comparable to those state-of-the-art results of pseudomorphic high electron mobility transistors. We also found that DCFETs are very ideal for single-voltage-supply operation. Degradation of device performance was observed for larger indium content (x=0.22), which is associated with strain relaxation in this highly strained channel. Experimental results showed that Ga0.51In0.49P/InxGa1−xAs/GaAs DCFETs with indium content x between 0.15 and 0.20 were very suitable for microwave high power device applications.